This revised application requests funds for upgrading the flow cytometry instrumentation within a established multi-departmental facility at the Johns Hopkins School of Medicine. Specifically, we are requesting funds to upgrade our current cell sorter, a dual laser - FACStarplus to state of the art high speed sorting capabilities. This request is driven by the scientific demand for high speed sorting capability specifically for the isolation of rare and minor cell subpopulations. The facility was established in 1989, in part, through the funding of a shared instrument grant. The current instrumentation has proven to be invaluable in forwarding the research mission of the users. However, there is increasing demand on the isolation of rare cell populations for functional and molecular analysis. The capacity of the current instrument sets a practical limit on our ability to respond to the increasing demand to identify, analyze and isolate minor and rare cell subpopulations. Within this proposal, 7 major research groups describe their current and future research activities and how these activities will benefit from the requested upgrade for high speed sorting. The multi-departmental flow cytometry facility has a established plan that has been operational since 1989 to ensure long term access, maintenance and availability of the instrumentation. The facility is staffed by a full-time manager/operator and is overseen by a facility director and a advisory committee. The facility has been annually funded through a blend of user fees, peer-reviewed funding of center and program projects and Institutional resources. This commitment will continue so that the facility maintains its ability to provide "state of the art" instrumentation to meet the flow cytometry needs of the Hopkins Biomedical Research community.